Microstructure development during the thermal oxidation of silicon in chlorine containing ambients

Monkowski, M.D.; Monkowski, J.; Tsong, I. S. T.; Stach, J.; Tressler, R. E.

doi:10.1016/0022-3093(82)90119-3

Cited by 9 publications

(12 citation statements)

References 3 publications

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“…If the density were about half that of SiO~, it would mean an Si concentration of -10~2/cm3 and an oxygen concentration of -2 • 1022/cm ~. This would be consistent with a molecular composition such as Si203C1~ as suggested by several authors (19,20). Such compounds have been identified in the gas phase (21).…”

Section: Initial Oxide Thickness (Nm)supporting

confidence: 75%

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Cl Incorporation at the Si / SiO2 Interface during the Oxidation of Si in HCl / O 2 Ambients

Tsai¹,

Butler²,

Williams³

et al. 1984

J. Electrochem. Soc.

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Transmission and analytical electron microscopy, nuclear backscattering, and secondary ion mass spectroscopy have been used to study the incorporation of C1 at the Si/SiO2 interface during the oxidation of Si. Oxidations were carried out in the range of 1100~176 for 10-120 min and with HC1 additions from 1-13%. It was found that a critical concentration of C1 (2 • 10~Scm -2) is required before a Cl-rich phase is observed. X-ray microanalysis indicates that the matrix in the interfacial region still contains at least about 2 • 1015 cm -2 as the Cl-rich phase forms. These two observations suggest that the Cl-rich phase formation takes place in order to reduce the reacted C1 supersaturation.in the SiO2 matrix. Agglomerates, whose growth occurs by thickening and/or coalescence phenomena, are the final morphology observed during the continuing C1 incorporation. Models relating Na-ion passivation to the Cl-rich phase are shown to require modification in terms of the microstructural development.The oxidation of silicon in chlorine-containing ambients is known to cause chlorine incorporation into the SiO2 near the Si/SiO2 interface il,. 2). For several oxidation conditions, phase separated regions have been observed (4-6). It has been asserted that both chlorine incorporation and sodium neutralization are related to the development of the Cl-rich phase formed at the Si/SiO2 interface (3-5).Recent CI concentration vs. distance profiles through the bulk oxide determined by secondary ion mass spectroscopy (SIMS) were interpreted to be the result of fieldaided diffusion (7). The profiles show the chlorine concentration to increase exponentially toward the Si/SiO2 interface where a peak occurs. Auger analysis-sputter profiles indicate the interface C1 peak is <~3 nm thick (7, 8). This peak is presumably the result of the Si/SiO2 interface acting as a "sink of the electrochemical potential" for C1 (7). Simple steady-state diffusion models have been proposed to describe the C1 incorporation as a function of oxide thickness (7-9).To improve the understanding of C1 incorporation, we have carried out detailed determinations of both the Si/SiO2 interface microstructure and the chlorine concentration and its lateral distribution along the interface. The interface morphology was determined by transmission electron microscopy (TEM). The total C1 content was obtained using nuclear backscattering (NBS) measurements (1, 2). The analytical electron microscope (AEM) [i.e. with the microscope operating in scanning transmission (STEM) mode] was .used to determine the local C1 concentration at the interface. The CI concentration profile was investigated in depth on several samples by SIMS. The effect of the initial oxide thickness on the chlorine incorporation process has also been studied. These results will be discussed with the objective of trying to understand the processes controlling chlorine incorporation. The relationship between the Cl-rich phase morphology and the Na-ion passivation models is briefly considered.

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Section: Initial Oxide Thickness (Nm)supporting

confidence: 75%

“…A similar argument has been suggested by Monkowski et at. (19). We suggested a composition for the phase of Si203C12.…”

Section: Initial Oxide Thickness (Nm)mentioning

confidence: 89%

Cl Incorporation at the Si / SiO2 Interface during the Oxidation of Si in HCl / O 2 Ambients

Tsai¹,

Butler²,

Williams³

et al. 1984

J. Electrochem. Soc.

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“…Because of the gas-phase reaction of HC1 and O2, the molecular species HC1, C12, 02, and H20 will be present in the OJHC1 oxidation ambient mixture and therefore in the oxide (5). In the present paper, C] profiles determir/ed by SIMS will be analyzed.…”

mentioning

confidence: 97%

“…Similar processes should determine the distribution of chlorine within oxide films fabricated by thermal oxidation of silicon in ambients containing HC1. Because of the gas-phase reaction of HC1 and O2, the molecular species HC1, C12, 02, and H20 will be present in the OJHC1 oxidation ambient mixture and therefore in the oxide (5). In the present paper, C] profiles determir/ed by SIMS will be analyzed.…”

mentioning

confidence: 99%

“…In this process C1 is incorporated into the SIO2, and is found to be segregated primarily near the Si/SiO2 interface (2)(3)(4). Recent C1 concentration vs. depth profiles determined by secondary ion mass spectrometry (SIMS) show a significant amount of C1 distributed in the oxide with increasing concentration toward the Si/SiO2 interface (5)(6)(7)(8)(9). One interpretation of these profiles was that the measured C1 was determined by the high temperature distribution of a mobile, diffusing C1 species (7).…”

mentioning

confidence: 99%

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The Distribution of Cl Impurities in SiO2 Films Produced by Thermal Oxidation of Si in Cl‐Containing Ambients

Sheu¹,

Butler²,

Feigl³

et al. 1986

J. Electrochem. Soc.

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C1 was introduced into SiO2 films by thermally oxidizing (100) Si in either OJHC1 or O2/C12 gas mixtures at llO0~ C1 concentration vs. depth profiles in these oxide films were determined by SIMS (secondary ion mass spectrometry). Analysis of the C1 distributions shows that, after incorporation into the SiO2 network at the interface, in the bulk of the growing oxide the bonded C1 is removed from the network. This process is analyzed quantitatively as a chemical reaction in which H20 reacts to replace C1 with OH. The kinetics of this replacement reaction and of the oxide film growth determine the C1 concentration vs. depth profiles in the grown films. The replacement reaction kinetics are faster when H20 is present than when only O2 is present. This accounts for the significantly different CI profiles in HCI oxides and Cl2 oxides. These observations are consistent with previous studies of the redistribution of implanted CI in oxide films during a second oxidation step.Oxidation of Si in chlorine-containing ambients is a widely used process in preparing gate oxide films for Si devices (1). In this process C1 is incorporated into the SIO2, and is found to be segregated primarily near the Si/SiO2 interface (2-4). Recent C1 concentration vs. depth profiles determined by secondary ion mass spectrometry (SIMS) show a significant amount of C1 distributed in the oxide with increasing concentration toward the Si/SiO2 interface (5-9). One interpretation of these profiles was that the measured C1 was determined by the high temperature distribution of a mobile, diffusing C1 species (7). The authors suggested that the C1 transport was by a "field-aided" diffusion process, against the concentration gradient. However, the origin of such a field was not established. In contrast, the C1 profile was suggested to be determined by a reaction-controlled process (9, 10). This difference has not been resolved. The question will be addressed in this paper.In a previous paper, we presented a semiquantitative analysis of C1 concentration profiles measured by SIMS (11). The profiles were obtained in the course of high temperature (900~ reoxidation of thermal oxide films implanted with C1; the analysis indicated that redistribution of the implanted C1 during the reoxidation step can be controlled by either reaction or diffusion. Which process dominates depends on the concentration of mobile molecular species (H~O or O2) capable of displacing chlorine species bonded into the SiO2 network (=-Si-C1) and on the relative magnitude of forward and reverse reaction rates in the displacement reaction. In fact, the redistribution process is slow and reaction limited in dry reoxidizing ambients (of order 1 ppm H20). It is fast and possibly diffusion limited in wet ambients (more than 1% H20).Similar processes should determine the distribution of chlorine within oxide films fabricated by thermal oxidation of silicon in ambients containing HC1. Because of the gas-phase reaction of HC1 and O2, the molecular species HC1, C12, 02, and H20 will be present in ...

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Modeling of the Oxide Growth in a Chlorine Ambient

Ling

Dupas

Meyer

1988

The Physics and Chemistry of SiO2 and the Si-SiO2 Interface

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Microstructure development during the thermal oxidation of silicon in chlorine containing ambients

Cited by 9 publications

References 3 publications

Cl Incorporation at the Si / SiO2 Interface during the Oxidation of Si in HCl / O 2 Ambients

Cl Incorporation at the Si / SiO2 Interface during the Oxidation of Si in HCl / O 2 Ambients

The Distribution of Cl Impurities in SiO2 Films Produced by Thermal Oxidation of Si in Cl‐Containing Ambients

Modeling of the Oxide Growth in a Chlorine Ambient

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